A memristor is a two-terminal device which has a resistance that is dependent upon the time integral of the magnitude and polarity of the voltage applied to it. One implementation of a memristor is a programmable resistor which utilizes the motion of dopants within a matrix to change the value of its resistance and hold that value until it is changed again. Thus this type of memristor retains a memory of experienced electrical conditions in the matrix.
A memcapacitor is a two-terminal device which has a capacitance that is dependent upon the time integral of the magnitude and polarity of the voltage applied to it. A memcapacitor can be designed to be a linear or nonlinear capacitor depending on the choice of and layout of materials used, and its programming.
While these new devices are revolutionary in being new forms of fundamental circuit elements, many challenges remain as circuits get smaller and quantum effects began to dominate the performance of integrated circuits. It would be desirable to further create electrical devices which could incorporate the characteristics of the new devices in a cost effective and flexible manner.